Self-expanding piston



J. A. BROCKMEYER SELF EXPANDING PISTON Filed July 16. 1925 sSheets-Sheet 1 Sept. 4, ,1 928.

wwaa J. A. BRocKMEYER? SELF EXPANDING PISTON Filed July 16, 1925Shams-Sheet 5 gwvewtoz L705e ifirval meyez;

I 61cm "was i citented Sept. 4, 1928.

UNITED STATES PATENT OFFICE.

SELF-EXPANDING PISTON.

Application filed July 16, 1925.

My invention relates to a new and useful improvement in pistons forinternal combustion engines as well as for all reciprocating engines,compressors or pumps in general. My invention relates more particularly,however, to a piston for the purpose set forth above which willfunction without any .packing means or medium, such as piston rings orthe like, and which will continue to function for a greater length oftime than pistons made heretofore, employing piston rings.

Nith the above ends in view, my invention consists of a pistoncomprising an inner core and an outer cylindrical piston shell made of alurality of segments throughout the circumierence of the piston, whichouter are secured and maintained at all times,

between the longitudinal contiguous edges of 'the several segments ofthe outer shell of the piston.

My invention consists of a novel construction in pistons of thecharacter stated, wherein any longitudinal movement between the innercore of the piston and the outer segmen s of the shell thereof, isentirely eliminated and whereby two portions of the pistons are'causedto travel back and forth as a unity.

My invention further consists of a novel construction and meansintermediate of said core and said segments of the outer shell, wherebythe latter will be forced radially outwardly and against the inner wallof the cylinder, with a constant pressure.

My invention further consists of novel oil retaining means in the outercylindrical sur-- face of the shell of said piston, whereby the oil willbe retained wit iin the crank case and prevented from entering thecombustion chamber past the piston.

For the. purpose of illustrating my invention, I have shown in theaccompanying drawings forms thereof which are at present preferred byme, since they will give in practice satisfactory and reliable results,although it is to be understood that the various instrumentalities ofwhich myinvention- Serial No. 43,908;

consists can be variously arranged and organized and that my inventionis not limited to the precise arrangement and organization of theseinstrumentalities as herein shown and described.

Referring to the drawings Figure 1 represents a View in elevation of apiston embodying my invention.

Figure 2 represents an elevational view of the inner core of the piston,embodying my invention.

Figure 3 represents an elevational vice? of the interior of one segmentof the outer shell of the piston.

Figure 4-. represents an elevational view of the exterior of'a segmentof the outer shell of the piston.

Figure 5 represents a plan Viewof the segment shown in Figures 3 and 4.

Figure 6 represents a sectional view of the piston taken on line 66 ofthe Figure 8.

Figure 7 represents a section on line 7*? of the Figure 6.

Figure 8 represents a section on line 8-8 of Figure 6.

Figure 9 represents an elevational view of a modified form of a pistonembodying my IHVGDt-IOIL Figure 10 represents a; section similar to thatshown in Figure 8,'embodying a. 1nodified form of joint constructionbetween the several segments of the outer shell.-

Figure 11 represents a similar sectional view of a piston embodyinganother modified form of joint construction between the several segmentsof the outer shell.

Referring to the drawings, in which like reference characters indicatelike parts, and with particular reference to the modification of myinvention shown in Figures 1 to 8 inclusive, 1 designates the inner coreof my novel piston, having the upper head 4 formed integral therewith,which head is adapted to receive the force of the explosion and totransmit the same to the rest of the core as well as to the outer shell5, of the piston, which surrounds said co e.

The outer shell 5 is composed of the three segments 6, 7 and 8, eachoccupying substantially one third of the circumference of the piston, asshown particularly in Figures 6,

and 8; an individual segment being shown in Figures 3 to 5 inclusive.

In order to interlock the inner core 1 with the several segments of theouter shell 5 of the piston, against any relative axial movement, eachof the segments-6, 7 and 8 is provided with the inner annular flanges 9and 10 res ectively, while the core 1 is provided wit the correspondingannular 'gro0ves11 and 12, which are adapted to i 10 and the walls ofthe grooves'll and 12 are substantially parallel and at right anglesto'the axis of the piston, thereby interlocking said core 1 and saidshell 5 against any relativeaxial movement, yet permitting a radialdisplacement of said shell with respect to said core. Thus the flange 11 formed near the lower end of the inner core 1 of the piston, serves toraise the shell upwardly when the piston is on its upward stroke, whilethe upper surface 13 serves to engage the outer s ell.

In order further to engage the outer shell 5 of the piston, on thedownward stroke of the same, and particularly in order to transmit theforce of the explosion directly to the outermost periphery of the shell,the head portion 4, of the core 1, is provided with a flange 15,extending out over and overhanging the upper edge of the shell 5-, andextending clear out to the'periphery of said shell as shown particularlyin Figures 2. and 6. The flange 15, being of substantially the samediameter as the cylindrical surface, also serves to center and guide thepiston, although it does not make a close fitting contact with the wallsof the cylinder.

Since the walls of the grooves 11 and 12, as well as the walls of theflanges 9 and 10 are substantially parallel and extend at right anglesto the axis of the piston, the segments 6, 7 and 8 of the piston arecapable of displacement relative to the core 1 radially outwardly, andat a right angle to the axis of the same.

The outward expansion of the segments 6, 7 and 8 is effected by means ofa series of springs or other tension means 16, interposed between thecore 1 and the several segments 6, 7 and 8, in a manner shownparticularly in Figures 2 to 8 inclusive. Thus, each of the segments 6,7. and-8, is provided with a flat spring 16 carried longitudinally ofthe axis of the piston, and supported at its two ends in two suitablerecesses 17, in the flanges 9 and 10, as shown particularly in Figures 3and 6. The springs 16 are preferably curved inwardly toward the centerof recesses, as shown in Figure 6, and are seated in correspondin curvedrecesses 18. By this means each of will be urged outwardly with aconstant force, in a direction indicated by the arrows 19.. Furthermore,due to the engagement of each of the segments at two points, near theupper and the lower extremities thereof respectively, that is, at thetwo flan es 9 and 10 respectively, the segments W51 be urged outwardlywith an even force at their upper and lower ends.

, In order to effect and maintain at hermetical seal or joint betweenthe longitudinal contacting edges of the several segments 6, 7 and 8 ofthe piston, various means may be resorted to. One of the constructionswhich has been found to be particularly eflicient in effecting a tightjoint between the edges of the piston segments and which has been foundto maintain a constantly fittingjoint under varying. conditions, andafter considerable wear, as will be occasioned by constant use, is shownin Figures 3, 4, 5, 7 and 8. Here the edges of the segments are rabbetedin a manner shown particularly in Figures 5, 7 and 8, that is, the twolongitudinal edges respectively, are provided with the tongue 20 and thegroove 21 which interlock with the corresponding groove and tongue onthe adjacent segments. In this form of joint construction, the tongueand groove are each provided with corresponding edges 22 and 23; beingsubstantially on a chord of the, circle of the piston, while the edges23 are formed substantially parallel to the arc of the circle of thepiston. On account of the relatively short extent of the ed es 23, theymay be straight instead of curve The contactin' edges of the segmentsare then continued inwardly along the surface 24 which forms to completethe oint. By this novel construction in a joint, the segments, whenurged outwardly in a substantially radial direction by the springs 16,

and retained by and against the inner surface of the cylinder, tend toexpand outwardly of the core at the several oints herein described,which joints will maintain perfect seal for a considerable amount ofactual expansion at the joints.

Thus as the iston wears, it will be seated more accurately in thecylinder and will thereby not lose any compression. Due to this constantoutward expansion of the out er shell or surface of the piston of mynovel construction, piston rings are entirely dispensed with, since thewall of the iston itselt. acts as the packingmeans. 11 order, however,to prevent the passage of oil ast the piston, I may provide one orsevera oil grooves 25 and 26 in the body of the shell 5 and extendingcompletely around the piston, throughout the several segments thereof.The oil collecting in the two grooves 25 and 26 during the operation ofthe piston,

the segment 6, 7 and 8 will not only be prevented from entering thecombustion chamber of the engine above the head 4, but is also caused totravel back and forth over the surface of the piston between said two'grooves as the piston 'reciprociites to and fro. Thus on the explosivestroke of the piston, the force of the explosion passing the upper edgeof the piston, will force some of the oil in the groove 25 downwardlyalong the surface of the piston into the lower groove 26; and similarlyupon the suction stroke of the piston the oil in the groove 26 will besucked up into upper groove 25, in each case the grooves25 and 26 actingas reservoirs to contain the oil and to prevent the further travel ofthe same. By this means, a more perfect lubrication of the contiguoussurfaces of the cylinder and piston is effected.

In Figure 9 I have shown a modification of my oil groove construct-ion,in which, in addition to the two oil grooves 27 and 28 there is providedan inclined surface 29, which recedes from the contacting c lindricalsurface of the piston, and there y does not contact with the walls ofthe cylinder. The contact surface 30, intermediate the upper groove 27and the central inclined surface 29 thereby acts as a piston ring toeffect a more perfect packing or contact of the piston with the wall ofthe cylinder.

In Figure 10 I have shown a modified form of joint construction,applicable to my novel piston segments 6, 7 and 8, which concave edges31 and convex edges 32, will per-,

mit of the expansion of the segments of the shell of the piston also toa considerable extent while maintaining a perfectly sealed joint betweenthe segments.

In Figure 11 I have shown a still further modification of a jointconstruction, wherein the joints are formed in the shape of a V with thecorresponding edges 33 and 34c telescoping into each other. 'In each ofthe .joint constructions it is seen that the contacting surfaces extendinwardly towards the center of the piston to a distance greater than thethickness of the wall of the shell 5, by the provision of thelongitudinal edge flanges 35 and 36, along each of the contacting edges?which extend clear back tothe inner core 1 of the piston as shownparticularly in Figures 3, 5, 7, 8, 10 and 11.

Having thus described my invention what I claim is new and desire tosecure by Letters Patent, is:

1. A piston comprising an inner core member, an outer shell surroundingsaid core and formed of a plurality of longitudinal segments, andresilient means operatively interposed between each of said segments andsaid core, urging the former outwardly of the latter in a yieldablemanner; the contiguous longitudinal edges of said segments beingalternately provided with opposed ton ue and groove portions extendinglongitudinally of said edges, which telescope into one another in theoperative position of said shell, thereby to seal the joint between saidedges.

2. A piston comprising an inner core member, an outer shell surroundingsaid core formed of a plurality of longitudinal segments, resilientmeans operatively inter posed between each of said segments and core,means for preventing any relative longitudinal displacement between thetwo, and for permitting a transverse radial displacement of saidsegments with respect to said core; the contiguous longitudinal edges ofsaid segments being provided with tongue and groove portionsrespectively, extending longitudinall of said e ges, which telescopeinto one anot er in the operative position of said shell, thereby toseal the joint between said edges.

3. A piston comprising an inner core member, an outer shell surroundingsaid core and formed of three longitudinal segments, and resilient meansoperatively interposed between each of said segments and said core,urging the former outwardly'of the latter in a yieldable manner; thecontiguous longitudinal edges of said segments being alternatelyprovided with opposed tongue and groove portions extendinglongitudinally of said edges which telescope' into one another in theoperative position of said shell, thereby to seal the joint between saidedges.

4. A piston comprising an inner core member, an outer shell surroundingsaid core formed of three longitudinal segments,

.a-resilient means operatively interposed between each of said so mentsand core, means for preventing any re ative longitudinal displacementbetween the two, and for permitting a transverse radial displacement ofsaid ,t-segments with respect to said core; the contiguous lon itudinaledges of said segments being provi ed with tongue and groove portionsrespectively, extending longitudinally of said edges, which telescopeinto one another in the operative position of said shell, thereby toseal the joint between said edges.

JOSEPH A. BRocKMEYER.

